Researchers uncover new gravitational wave characteristics

May 22, 2017
A visualization of a supercomputer simulation of merging black holes sending out gravitational waves. Credit: NASA/C. Henze

Monash researchers have identified a new concept - 'orphan memory' - which changes the current thinking around gravitational waves.

The research, by the Monash Centre for Astrophysics, was published recently in Physical Review Letters.

Einstein's theory of general relativity predicts that cataclysmic cosmic explosions stretch the fabric of spacetime.

The stretching of spacetime is called 'gravitational waves.' After such an event, does not return to its original state. It stays stretched out. This effect is called 'memory.'

The term 'orphan' alludes to the fact that the parent wave is not directly detectable.

"These waves could open the way for studying physics currently inaccessible to our technology," said Monash School of Physics and Astronomy Lecturer, Dr Eric Thrane, one of the authors of the study, together with Lucy McNeill and Dr Paul Lasky.

"This effect, called 'memory' has yet to be observed," said Dr Thrane.

Gravitational-wave detectors such as LIGO only 'hear'' gravitational waves at certain frequencies, explains lead author Lucy McNeill.

"If there are exotic sources of gravitational waves out there, for example, from micro black holes, LIGO would not hear them because they are too high-frequency," she said.

"But this study shows LIGO can be used to probe the universe for gravitational waves that were once thought to be invisible to it."

Study co-author Dr Lasky said LIGO won't be able to see the oscillatory stretching and contracting, but it will be able to detect the memory signature if such objects exist.

The researchers were able to show that high-frequency gravitational waves leave behind a memory that LIGO can detect.

"This realisation means that LIGO may be able to detect sources of that no one thought it could," said Dr Lasky.

Explore further: LIGO discovery named Science's 2016 Breakthrough of the Year

More information: Lucy O. McNeill et al. Detecting Gravitational Wave Memory without Parent Signals, Physical Review Letters (2017). DOI: 10.1103/PhysRevLett.118.181103

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Steelwolf
1.8 / 5 (5) May 22, 2017
Since there are various sorts of explosions happening regularly in most galaxies, this could well be what is responsible for the expansion rate of the universe, and also points towards there being a field that can be likened to the Ether that some have sought if it shows a 'stretching and staying' metric.
barakn
1 / 5 (5) May 22, 2017
Could orphan memory be Dark Energy?
El_Nose
5 / 5 (1) May 22, 2017
-- personal opinion

we have detected waves that are billions of light years from us --- you would need more than what these produce in my personal not done the math on a napkin yet opinion. Hubble expansion is has a noted acceleration rate, I don;t see how a static thing like quasars colliding creates something so pervasive to the entire universe in all directions at the same time.
boojay
4 / 5 (1) May 22, 2017
I have the same question. And if indeed all these innumerable collision/explosive events throughout the universe were responsible for dark energy due to this memory effect stretching out space after the fact, wouldn't that mean that eventually the expansion of space would slow down once space runs out of these events? If so, would gravity finally overcome dark energy? But then we'd run into the same issue...
Molecular hydrogen
3.2 / 5 (6) May 22, 2017
In my opinion not done the maths but Photons could be dark energy ... over Billions of years that tiny pressure from the tiny mass of Photons in all directions could cause movement plus you cant see Photons move you can only observe them when the hit an object. Im sure, if you could observe Photons travelling in all directions, the universe would appear brilliant white like a negative on a film ... just in my opinion
antialias_physorg
3.7 / 5 (9) May 22, 2017
In my opinion not done the maths but Photons could be dark energy ...

DM distribution has been calculated. This in no way conforms to the distribution of photons.
Molecular hydrogen
4.8 / 5 (5) May 22, 2017
Thanks for the information
Although i was under the impression the Dark matter and Dark Energy were different entities my mistake
Hyperfuzzy
1 / 5 (3) May 22, 2017
Could orphan memory be Dark Energy?

Sure

By the way, we are not observing the universe correctly. We must use common sense in defining what we see. You can define the stream we are a part; if, you can define whether you're seeing from inside the objects bubble and you are traveling faster than this surface, defines the acceleration. There exist only a finite set of states. So first, you are required to produced enough measurements, following Maxwell, this Truth is undeniable. Then, we begin to construct the universe without misinterpretation.

Oh, I thought you meant Orphan Annie, any way, with a false premise, anything is true.
Old_C_Code
2.1 / 5 (7) May 22, 2017
Steel: The space within galaxies is NOT expanding. The galaxies themselves are expanding away from one another. There's very little blue shift seen out there.
Benni
1 / 5 (4) May 22, 2017
Since there are various sorts of explosions happening regularly in most galaxies, this could well be what is responsible for the expansion


It's the 2nd Law of Thermodynamics better known as ENTROPY. Einstein described in General Relativity, quoting from Part III: Considerations on the Universe as a Whole
Albert Einstein 97
If we are to have in the universe an average density of matter which differs from zero, however small may be that difference, then the universe cannot be quasi-Euclidean. On the contrary, the results of calculation indicate that if matter be distributed uniformly, the universe would necessarily be spherical (or elliptical). Since in reality the detailed distribution of matter is not uniform, the real universe will deviate in individual parts from the spherical, i.e. the universe will be quasi-spherical. But it will be necessarily finite. In fact, the theory supplies us with a simple connection between the space-expanse of the Universe & average density
Zzzzzzzz
5 / 5 (1) May 22, 2017
Steel: The space within galaxies is NOT expanding. The galaxies themselves are expanding away from one another. There's very little blue shift seen out there.

Not the way I understand it....
Hyperfuzzy
1.3 / 5 (4) May 22, 2017
Whatever, first know what you are looking upon. The speed of light is the Original_Wavelength/Observed_Period, this can exist from 0 to infinity. If charge is never created or destroyed, the universe is infinite. Therefore, unlikely everything is traveling away. Recall that speed implies a Velocity is + or -.

Gravitational Waves do not exist, the waves created with mass are created from the bipolar constituents of mass. Charge does not have mass. There only exist EM waves. These waves are the wrinkles created when a charge oscillates. Let's not misinterpret observation with fantasy.

Also don't underestimate the potentials or how thet oscillate.
ursiny33
1 / 5 (2) May 22, 2017
Photons probably decay and power down to dark matter , after one hundred billion years far from magnetic fields of the hydrogen atom based construction of matter
ursiny33
2.3 / 5 (3) May 22, 2017
Photons do not have an eternity as a lifespan, they become dark and turn back into the parts
sascoflame
1 / 5 (1) May 22, 2017
In my opinion not done the maths but Photons could be dark energy ... over Billions of years that tiny pressure from the tiny mass of Photons in all directions could cause movement plus you cant see Photons move you can only observe them when the hit an object. Im sure, if you could observe Photons travelling in all directions, the universe would appear brilliant white like a negative on a film ... just in my opinion


Photos that cannot be absorbed by electrons could be dark matter. Energy is mass and light has mass and will respond to gravity. The problem is photons do not behave like dark matter.
Da Schneib
3 / 5 (4) May 22, 2017
One wonders how these areas of memory would affect star formation after mergers. This could be a watershed for simulations-- or a rock on which they founder.
Molecular hydrogen
1 / 5 (1) May 23, 2017
Thanks Sascoflame for the info.
In my opinion i have always considered Dark energy and Dark Matter as separate entities meaning Photons as Dark Energy providing the momentum with molecular Hydrogen as Dark matter not to be confused with Atomic hydrogen. Research done by Paul Marmet in 1990 is a valuable insight
Discovery of H2, in Space
Explains Dark Matter and Redshift
by Paul Marmet
But i guess its back to the drawing board for me now
baudrunner
not rated yet May 23, 2017
The stretching of spacetime is called 'gravitational waves.'
Well, thanks for clearing that up.

How does one separate the "shock" wave from a "gravitational wave"?

@Molecular hydrogen: you don't know what a photon is. What it isn't is a particle that shoots off through space bouncing off stuff as it illuminates everything until it hits your retina. Light as such does not even exist. It is an interpretation of your brain based on the bio-electric signals resulting from the stimulation of the cones and rods on your retinas converting that information into something your occipital lobe can make sense of.
sedakamix
1 / 5 (1) May 23, 2017
A new theory put forward is Dark Matter is stretched Dark Energy , Produced by 2 stage black hole . front running particle from "big clash" leads until its rejected by dark Energy , creates a dent in dark energy 2 alive particles fall in, twisting the dark energy inwards in all dimensions along with more matter . After weight has reached maximum load it crushes one of the live particles dead, matter is free to let go. Space or Dark Energy springs back creating SUPERNOVA but space is damaged , The damage is sagging Dark Matter in those damaged sagging peeks and valleys galaxies are formed . All sizes all over Space the front runner particles from the Big Clash effect each area of dark energy, so some parts of universe look like inflation but its just , Dark Energy returning to its normal state . But its damaged forever .
Molecular hydrogen
not rated yet May 24, 2017
Photons are actually electromagnetic energy and an elementry particle. We actually only view reflected light.
Mr Angry i do really find you amusing but on a serious note you need to see someone about your blood pressure and your stress level have a good day now
antialias_physorg
3 / 5 (2) May 24, 2017
One wonders how these areas of memory would affect star formation after mergers.

Not sure if it would be much of an issue after mergers. Once the dance of two stars stops the gravitational waves cease.

The space within galaxies is NOT expanding.

Why not? Note that space expanding in galaxies wouldn't mean that stuff within a galaxy would move farther away from each other. The orbit of gravitational bound masses is determined by their velocity. Let's assume (naively, as an example only) that space in our solar system is expanding between the Sun and the Earth. So Sun-Earth distance increases, but velocity of the Earth does not. However, orbital distance is a function of (tangential) speed so Earth immediately 'falls' back to the old distance. We could be moving through an expanding space without much of an influence on us.

(There should be measurable influences as everything around us will exhibit a red shift: The further away the more. Which is observed.)
Da Schneib
3 / 5 (4) May 24, 2017
One wonders how these areas of memory would affect star formation after mergers.

Not sure if it would be much of an issue after mergers. Once the dance of two stars stops the gravitational waves cease.
The article says,
After such an event, spacetime does not return to its original state. It stays stretched out. This effect is called 'memory.'
If the article is right and we can detect this, that means it can have a lasting effect. This is a candidate for the effect that seems to cause a slowing of star formation in galaxies with AGNs.
antialias_physorg
4 / 5 (4) May 24, 2017
The article says,

After such an event, spacetime does not return to its original state. It stays stretched out. This effect is called 'memory.'

Well, I don't see how the effect would change star formation processes after mergers. I could see how this would affect star formation rates. But the processes? I'm not sure where you're seeing a change, there.
idjyit
5 / 5 (1) May 24, 2017
Surely they mean the wave of stretched space continues to be stretched how else would LIGO detect it ?
Can't see it having much affect on star formation it's only stretched space no gravity.
And it wont remain local either.
Da Schneib
3.7 / 5 (6) May 24, 2017
@antialias and @idjyit, I make no speculations about mechanism. I note a few things:

1. A merger of black holes creates powerful gravitational waves.
2. After these waves have passed there is some sort of residual geometric effect on spacetime. Or so this article asserts.
3. Geometric effects on spacetime are gravity.
4. Changes in gravity can hardly avoid affecting star formation.
5. Mergers appear, according to recent research, to form AGN.
6. Galaxies with AGN show differences in star formation.

I'll leave you to consider the possibilities here. I'm merely speculating, but not, I think, without cause.
idjyit
3.3 / 5 (3) May 24, 2017
1. A merger of black holes creates powerful gravitational waves.
They produce spacial length disturbances which are referred to as Gravitational Waves.

2. After these waves have passed there is some sort of residual geometric effect on spacetime.
I don't believe so. The wave is the memory, I'm not sure what they mean by "Parent" wave,
But I'm guessing they are talking about supertones

3. Geometric effects on spacetime are gravity.
Effects of gravity not gravity itself.

Da Schneib
3.4 / 5 (5) May 24, 2017
3. Geometric effects on spacetime are gravity.
Effects of gravity not gravity itself.
Gravity itself is geometric effects on spacetime.

If you believe Einstein.

I won't bother with the rest; you're more interested in playing semantic games than finding anything interesting out. Bye now.
idjyit
3 / 5 (2) May 25, 2017
Come of it buddy, I'm trying to actually have a discussion.

You obviously don''t even know how LIGO works.

I'll ignore you from now on.
Da Schneib
4.2 / 5 (5) May 25, 2017
OK, then, I'll take you at your word.

1. A merger of black holes creates powerful gravitational waves.
They produce spacial length disturbances which are referred to as Gravitational Waves.
No, this is gravitational energy, just as light waves are EM energy. It's just as proper to call them gravitational waves as it is to call them spatial distortions.

After these waves have passed there is some sort of residual geometric effect on spacetime.
I don't believe so.
Then you don't believe this article.

The wave is the memory, I'm not sure what they mean by "Parent" wave,
By "parent" they mean the gravitational wave train that was emitted when the black holes coalesced. They are referring to a persistent effect in spacetime that remains after the gravity waves have passed.

But I'm guessing they are talking about supertones
I don't know what supertones are.
Dingbone
May 25, 2017
This comment has been removed by a moderator.
Benni
1 / 5 (2) May 25, 2017
"Researchers uncover new gravitational wave characteristics"

This entire gravitational wave discussion boils down to detection of the CHANGE OF INTENSITY of the force field that gravity exerts upon the detector's sensors. They are measuring a change of intensity that occurs at light speed in accordance with the Inverse Square Law, nothing more.
Hat1208
3.9 / 5 (7) May 25, 2017
@DaSchneib

But I'm guessing they are talking about supertones

I don't know what supertones are.

Neither does he. But he saw the word somewhere.

@idjyit

If you are trying to have a conversation DaSchneib is one of the people on this site that will converse in a polite manner and most of what he states is based on science not religion.
JSYK
Benni
2 / 5 (4) May 25, 2017
If you are trying to have a conversation DaSchneib is one of the people on this site that will converse in a polite manner and most of what he states is based on science not religion.


Sure, like the "science" he promotes that infinite gravity wells & infinite density can exist inside the confines of a finite stellar mass contrary to the Inverse Square Law, then claims such "science" is found inside Einstein's General Relativity, and when I ask him to quote the section of GR in which this so called "science" is found, he goes on a name calling binge.............yeah, real "polite manner".
Hyperfuzzy
1 / 5 (2) May 25, 2017
If you place all charge at a single point, infinite density. Its bipolar. Although possible, assembly is tricky. The result, well, if the center of each field is at the same point, no gravity. If at different points, i.e. assembly, the delta for the potential fields will yield a gravity field, it's always oscillating.

Gravity is a misnomer, juz say'n
idjyit
4 / 5 (1) May 25, 2017
A supertone is the sum of two wave forms , it's a musical term which I tend to use but it simply means harmonics created by two wave forms being measured simultaneously or in math, added together.

LIGO detects differences in space using a two lasers that measure distance, this is an affect of gravity created at the source. If one laser beam has traveled a greater distance the destructive interference pattern changes and light can be measured.

Stretched space is not gravity it is an affect of gravity, an affect that is more persistent than the gravity that caused it, which is why they call it memory.

From this article ...
"The stretching of spacetime is called 'gravitational waves.'"
Da Schneib
3.7 / 5 (3) May 25, 2017
@idjyit, I've never heard of supertones in either music theory or mathematics. Harmonics are a complete different subject; are you perhaps thinking of superposition of waves?

You're more-or-less correct about how LIGO works; it's actually quite a bit more complex than that, but you've got the general idea.

Stretched space is not separate from gravity. The article is actually incomplete in its statement; gravity waves are both stretched and compressed space.

The stretching and compression are both gravity. Each deviates from flat space, and each therefore represents a given value of the gravity field.

What this article appears to be referring to is an effect that remains in the space traversed by the gravity waves after the gravity waves have moved on, and that's very different from simply having a gravity wave or train of them go by.
Benni
1 / 5 (1) May 25, 2017
The stretching and compression are both gravity. Each deviates from flat space, and each therefore represents a given value of the gravity field.
....nope, not what Einstein wrote in GR, here, read it:

Part III: Considerations on the Universe as a Whole
Albert Einstein 97

"If we are to have in the universe an average density of matter which differs from zero, however small may be that difference, then the universe cannot be quasi-Euclidean. On the contrary, the results of calculation indicate that if matter be distributed uniformly, the universe would necessarily be spherical (or elliptical). Since in reality the detailed distribution of matter is not uniform, the real universe will deviate in individual parts from the spherical, i.e. the universe will be quasi-spherical. But it will be necessarily finite. In fact, the theory supplies us with a simple connection 1) between the space-expanse of the universe and the average density of matter in it.
Da Schneib
5 / 5 (1) May 25, 2017
@Lenni is trolling again.

Do some math, @Lenni.

Just as a reminder:
-m'' + m'n' - m'² - 2m'/r = 0
m'' + m'² - m'n' - 2m'/r = 0
e⁻²ⁿ (1 + m'r - n'r) - 1 = 0
R₂₂ sin² ϕ = 0
Source: http://www.etsu.e...esis.pdf
And another reminder:
E² = (pc)² + (mc²)²
https://phys.org/...rgy.html
https://phys.org/...ole.html
Da Schneib
5 / 5 (2) May 25, 2017
One additional note: as the article says, quoting one of the authors of the paper, this memory effect has never actually been measured. So take all this with a grain of salt.
idjyit
5 / 5 (1) May 25, 2017
"What this article appears to be referring to is an effect that remains in the space traversed by the gravity waves after the gravity waves have moved on, and that's very different from simply having a gravity wave or train of them go by."

No that is simply not true, have a look at the abstract for the article itself, they talk of (using your term) the superposition or standing wave created by much higher frequency events (parents).
(The wave form images explain it quite clearly)

What you are trying to say is the equivalent of RF wave frequencies are in fact the AC current that created them.

How would LIGO detect a Gravitational effect in local space thousands of light-years away ?
Da Schneib
5 / 5 (2) May 25, 2017
I've not only had a look at the abstract of the paper, I've investigated the actual memory effect they're talking about. It turns out that there is an earlier paper suggesting that they might be able to measure the memory effect by measuring an ensemble of GW events. https://arxiv.org...1415.pdf You'll find that the same Eric Thrane who is a co-author of the paper this article is about is also a co-author on that one. A review of this paper and a couple of others on the subject will convince you that what these people are saying is pretty simple:

A GW detector in free space, as opposed to LIGO, might be able to measure the memory effect directly. The passage of a GW would leave free floating test masses used by such a detector in a different position than they were before the GW passed. This would be unambiguous evidence of this memory effect.
[contd]
Da Schneib
5 / 5 (2) May 25, 2017
[contd]
It is also substantive proof that such an effect would indicate a permanent alteration of spacetime, since we measure spacetime by the movements of inertial objects in it. So I'm pretty sure your claim,
No that is simply not true
is incorrect. In addition, this is not an effect of just any gravity waves; it is an effect that is caused by the ringdown portion of the wavetrain. It is absent before this ringdown, and present after, at least if the math from which this prediction was derived is correct.

As for LIGO detecting it, an ensemble of GW detections would be used, rather than a single one. See the paper I linked above for details; it's on arXiv so the complete text is available.

This paper suggests free fall experiments like LISA might be better at detecting this effect, as I suggested in my previous post: https://arxiv.org...3486.pdf

[contd]
Da Schneib
4 / 5 (4) May 25, 2017
[contd]
Finally, your claim that it would be necessary for LIGO to detect spatial expansion local to the event that created the GWs is incorrect. Detecting the memory effect locally to LIGO would show not only that it exists, but that it must exist everywhere gravity waves have passed. And like EM radiation, gravity radiation is inverse square; thus it would be far stronger near the event than near the detector.

So I think you've (at the kindest) misinterpreted what is being claimed in the article, misinterpreted what I've said, don't understand any of the papers relevant to the subject, and have introduced idiosyncratic terminology no one else understands.
Da Schneib
5 / 5 (2) May 25, 2017
It's worth mentioning that this was previously believed to be impossible with LIGO because its test masses (the mirrors) are returned to neutral position after the passage of a GW by magnets. However, the use of an ensemble of measurements, as suggested in the paper I linked above, might overcome this limitation. LISA, since it is in free space, would not have this limitation and hopefully looking for this will be on the science program now that we know it might be there.
Da Schneib
5 / 5 (2) May 25, 2017
Last but not least, another badly written PhysOrg article. Lots of holes in this one. Start with describing the memory effect in greater-than-third-grade terms. Move on to discussing the evidence that would show if this effect actually exists, rather than speculating about what's going on a million light years away, then show how what's going on a million light years away can be proven by what we can see right here.

I learned more in 5 minutes reading the actual papers than I did in 10 minutes reading PhysOrg.

Do better, PhysOrg.
idjyit
5 / 5 (2) May 25, 2017
Fair enough, thanks for the links.
Da Schneib
5 / 5 (3) May 25, 2017
@idjyit, sure. It was worth my time; I figured out what PhysOrg was limping along trying to describe in terms so simplistic no one could figure it out. I'll even give you cred for being deceived by their treatment that invokes an effect in distant galaxies without talking about it happening right here on Earth.

Worth mentioning that such an effect would affect star formation by interrupting the concretion of gas and dust clouds in galaxies, by pushing the gas and dust apart where the stars would ordinarily form, so this becomes a stronger hypothesis as to why AGN containing galaxies have interrupted star formation-- assuming of course we can confirm the effect.
idjyit
5 / 5 (2) May 26, 2017
Agreed, the implications would be far reaching
antialias_physorg
5 / 5 (2) May 26, 2017
1. A merger of black holes creates powerful gravitational waves.
2. After these waves have passed there is some sort of residual geometric effect on spacetime. Or so this article asserts.
3. Geometric effects on spacetime are gravity.
4. Changes in gravity can hardly avoid affecting star formation.
5. Mergers appear, according to recent research, to form AGN.
6. Galaxies with AGN show differences in star formation.

I guess I was misreading your first post to imply that the *way* stars form would change rather than the rate. I agree that the rate will change due to different gravity profile after a gravitational wave has passed. If the wave leaves space stretched it would slow accretion in that region.)

Though the effect would likely be tiny anywhere but very close to the event that created the gravitational wave- but since it's one-way cumulative it might add up over many events.
Da Schneib
5 / 5 (1) May 26, 2017
I don't have a good feel for how much interference with gas and dust clouds would be needed for a change in the rate of star formation; this effect might not be strong enough to do much. Then again, there might be a critical point, and it might not take much. We'll have to watch and see first whether they can actually detect it, I think.

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